Reaction injection molded polyurethanes are well known in the art as described in a paper entitled "THE BAYFLEX 110 SERIES--THE NEW GENERATION OF RIM MATERIALS", by W. A. Ludwico and R. P. Taylor presented at the SOCIETY OF AUTOMOTIVE ENGINEERS PASSENGER CAR MEETING, Detroit, Mich., Sept. 26-30, 1977; a paper entitled "THE PROPERTIES OF HIGH MODULUS RIM URETHANES", by R. M. Gerkin and F. E. Critchfield presented at the above meeting; British patent No. 1,534,258 titled "PROCESS FOR THE PRODUCTION OF ELASTOMERIC POLYURETHANE-POLYUREA MOULDED PRODUCTS HAVING A COMPACT SURFACE SKIN" and a book by F. Melvin Sweeney entitled INTRODUCTION TO REACTION INJECTION MOLDING, Technomics, Inc., 1979.
These systems employ, as chain extenders, diols, aromatic amines, cyanoethylated polyoxyalkylene amines and mixtures thereof.
It has been thought that as a general rule the aliphatic amines are too fast to be suitably employed in RIM urethane applications. It has now been discovered that certain quantities of aliphatic amines enhance certain properties such as one or more of those selected from, for example, flexural modulus, impact strength, tear strength, heat resistance and the like can be improved by their use in such RIM urethane systems usually without an unacceptable reduction in other properties of the polymer.